Field of the Invention
The present invention relates to a superconducting coil and a superconducting device, and in particular, to a superconducting coil that includes a plurality of laminated pancake coils and is used in a superconducting device, such as a superconducting magnet or a superconducting rotary machine, and a superconducting device including the superconducting coil.
Description of the Related Art
In a superconducting device, such as a superconducting magnet or a superconducting motor, a plurality of laminated pancake type superconducting coils may be used. Various structures, such as a structure in which laminated pancake type superconducting coils are cooled by heat conduction from a freezing machine or a structure in which laminated pancake type superconducting coils are cooled by coolant such as helium gas, have been suggested.
As a conventional example of a pancake type superconducting coil, a superconducting coil impregnated with resin for electromagnetic force reinforcement and a superconducting coil integrated by curing a glass fiber reinforced sheet, which is interposed between laminated pancake coils and contains semi-cured resin, is known (refer to Japanese Unexamined Patent Application, First Publication No. H6-151168).
FIG. 4 shows a conventional example of a superconducting coil integrated by curing semi-cured resin contained in a glass fiber reinforced sheet. A superconducting coil 100 in this example includes a vacuum container 101, a heat shield container 102 provided inside the vacuum container 101, and a coil laminate 103 provided so as to be surrounded by the heat shield container 102. In the coil laminate 103, a plurality of pancake coils 105 formed by winding a superconducting wire into a pancake shape are laminated vertically and coaxially along a body portion 107 of a bobbin 106. The coil laminate 103 is housed inside the heat shield container 102. In the superconducting coil 100, a glass fiber reinforced sheet 108 is inserted between laminated pancake coils 105, and the laminated pancake coil 105 and the glass fiber reinforced sheet 108 are bonded together. A freezing machine 109 passing through the vacuum container 101 and the heat shield container 102 in a vertical direction is provided above the bobbin 106. The superconducting wire that forms the pancake coil 105 can be cooled by conduction cooling using the freezing machine 109.
In the conventional superconducting coil 100 in which the glass fiber reinforced sheet 108 and the pancake coil 105 are integrated as shown in FIG. 4, however, when one or more of the pancake coils 105 deteriorate, the entire superconducting coil 100 should be manufactured again. In this case, there is a risk of serious damage in terms of time and cost.
In particular, when a rare earth element-based oxide superconducting wire is used, it is generally difficult to detect the occurrence of the quench. For this reason, if a part of the superconducting wire that forms the pancake coil 105 is burnt, the entire superconducting coil 100 should be remanufactured. Therefore, there is a problem in that serious damage is caused in terms of time and cost.
In view of the damage in terms of time and cost, it is also possible to adopt the superconducting coil 100 in which the glass fiber reinforced sheet 108 and the pancake coil 105 are not integrated. However, in order to ensure the mechanical strength of the superconducting coil 100 and increase the thermal stability of the entire coil, it is desirable to integrate the pancake coil 105 impregnated with resin and the glass fiber reinforced sheet 108.
The present invention has been made in view of the above, and it is an object of the present invention to provide a superconducting coil, which includes a plurality of pancake coils formed by winding a superconducting wire and has a structure in which, even if a problem occurs in one or more of the assembled pancake coils for some reason, the pancake coil in which the problem has occurred can be replaced, and a superconducting device including the superconducting coil.